Functions

The VPSS module receives images sent by the VI/VDEC module, and performs cropping, resizing, and fisheye correction on the images. In addition, the VPSS module outputs dual-channel images with different resolutions from the same source for encoding, previewing, or snapshot.

You can call the hi_mpi_sys_bind interface to bind the VI/VDEC video streams to the VPSS and send the video streams to the VPSS for further processing. The VPSS provides the corresponding processing capability based on the group and the channel in the group, and outputs the images to the user or lower-level modules (such as the VO).

Concepts related to the VPSS are described as follows:

• Group

  The VPSS provides the concept of group for users. Each group shares the VPSS hardware resources in time division multiplexing (TDM) mode.

• Channel

  A VPSS group provides multiple channels, and each channel has independent functions such as resizing and fisheye correction.

• FRC

  Stands for frame rate control and is classified into group frame rate control and channel frame rate control based on the control point.

  • Group frame rate control. When hi_mpi_vpss_create_grp is used to create a group, the frame rate control attribute can be used to control the receiving of input images by each group.
  • Channel frame rate control. When hi_mpi_vpss_set_chn_attr is used to set the group channel attributes, the frame rate control attribute can be used to control the processing of each channel image.
• CROP

  Crops a specified region from an image.

• 3DNR

  Used for three-dimensional noise reduction. After related parameters are configured, the Gaussian noises can be removed from images. This enables the images to become smoother and reduces the encoding bit rate.

• Mosaic

  The mosaic function is used to fill a specified region of the VPSS output image with mosaic blocks. This function must be used together with the region management function.

• Cover

  A Cover region can be used to fill the output image of the VPSS with a pure color block. This function must be used together with the region management function.

  The coordinates of a Cover region can be absolute coordinates or relative coordinates.

• Aspect Ratio

  The aspect ratio specifies the ratio of the width to height of the output image relative to the input image.

• OverlayEx

  Video overlay region, which is used to overlay a bitmap on an output image in a VPSS physical channel. This function must be used together with the region management function.

• FISHEYE

  Performs fisheye correction.

• Scale

  Scales up or down images. The scaling multiple indicates the horizontal or vertical scaling multiple.